Effect of quaternary ammonium salts on the extraction of 1,3-propanediol with phenylboronic acid

Abstract

The microbial production of 1,3-propanediol from renewable resources is of great interest. However, its strong hydrophilic property makes the separation of 1,3-propanediol from the fermentation broth difficult. In this study, reactive extraction using boronate esterification, and anion exchange with a quaternary ammonium salt were utilized to extract 1,3-propanediol from an aqueous solution. For this process, the effects of the quaternary ammonium cation and the counter anion on the extraction were examined. Symmetrical quaternary cations were found to provide higher distribution ratios than their unsymmetrical counterparts. Following this, quaternary ammonium fluoride and hydroxide (which have smaller association constants than commercially available quaternary ammonium salts) were prepared. It was found that the distribution ratio of symmetrical quaternary ammonium hydroxide such as [N8,8,8,8][OH] increased by roughly double that for Aliquat 336.